Mini-grid

A mini-grid is an aggregation of electrical loads and one or more energy sources operating as a single system providing electricity and possibly heat, isolated from a main power grid. A modern mini-grid may include renewable- and fossil fuel-based power generation, energy storage, and load control.^[2][3] A mini grid can be fully isolated from the main grid (wide area synchronous grid) or interconnected to it. If it is interconnected to the main grid, it must also be able to isolate (“island”) from the main grid and continue to serve its customers while operating in an island or autonomous mode.^[4] Mini-grids are used as a cost-effective solution for electrifying rural communities where a grid connection is challenging in terms of transmission and cost for the end user population density,^[5] with mini-grids often used to electrify rural communities of a hundred or more households that are 10 km or more from the main grid.^[6]

Mini grids and microgrids are similar, and the terms are sometimes used as synonyms. Both microgrids and mini grids include generation and distribution, and generally include electricity storage in the form of electrochemical batteries. Both can “island” in the event of a blackout or other disturbance or – common in mini grids – in the case that they were never connected to the main grid in the first place. In practice, the term “mini grid” is used more in a context common in low- and middle-income countries providing electricity to communities that were previously unelectrified, or sometimes used to provide reliable electricity in areas in which the national grid is present but where electricity is sporadic. Across Sub-Saharan Africa, more than half of households connected to the main grid reported receiving electricity less than half of the time.^[7] The African Mini Grid Developers Association (AMDA) reports that uptimes of mini grids of its members for which data was available averaged 99% across countries.^[8] In contrast, the term “microgrid” is used more in higher income countries to refer to systems that provide very high levels of reliability (for example, “five nines” or 99.999%) for critical loads like data centers, hospitals, corporate campuses or military bases generally in service areas that already have high levels of reliability (e.g. “three nines” or 99.9% reliability) by global standards.^[9][10]